docs: def get_data_mask_functions(is_micro):
      """
      Returns the data mask functions.
  
      ISO/IEC 18004:2015(E) -- 7.8.2 Data mask patterns (page 50)
      Table 10 — Data mask pattern generation conditions (page 50)
  
      ===============     =====================   =====================================
      QR Code Pattern     Micro QR Code Pattern￼  Condition
      ===============     =====================   =====================================
      000                                         (i + j) mod 2 = 0
      001                 00                      i mod 2 = 0
      010                                         j mod 3 = 0
      011                                         (i + j) mod 3 = 0
      100                 01                      ((i div 2) + (j div 3)) mod 2 = 0
      101                                         (i j) mod 2 + (i j) mod 3 = 0
      110                 10                      ((i j) mod 2 + (i j) mod 3) mod 2 = 0
      111                 11                      ((i+j) mod 2 + (i j) mod 3) mod 2 = 0
      ===============     =====================   =====================================
  
      :param is_micro: Indicates if data mask functions for a Micro QR Code
              should be returned
      :return: A tuple of functions
      """
      # i = row position, j = col position; (i, j) = (0, 0) = upper left corner
      def fn0(i, j):
          return (i + j) & 0x1 == 0
  
      def fn1(i, j):
          return i & 0x1 == 0
  
      def fn2(i, j):
          return j % 3 == 0
  
      def fn3(i, j):
          return (i + j) % 3 == 0
  
      def fn4(i, j):
          return (i // 2 + j // 3) & 0x1 == 0
  
      def fn5(i, j):
          tmp = i * j
          return (tmp & 0x1) + (tmp % 3) == 0
  
      def fn6(i, j):
          tmp = i * j
          return ((tmp & 0x1) + (tmp % 3)) & 0x1 == 0
  
      def fn7(i, j):
          return (((i + j) & 0x1) + (i * j) % 3) & 0x1 == 0
  
      if is_micro:
          return fn1, fn4, fn6, fn7
      return fn0, fn1, fn2, fn3, fn4, fn5, fn6, fn7